This work's purpose is to examine the influence of the aging process upon the development and enactment of automatic and effortful attentional processes. The purposes are accomplished through controlled laboratory studies. The results of a study investigating the development of automatic visual detection of representatives of semantic categories in young, middle-aged, and old adults, reported in FY86, found old adults unable to attain automatic detection after 4200-5700 trials of practice. The task was visual search where 1-3 semantic categories were memorized then searched for in two-word visual displays. Automatic detection of the memorized categories occurred when the time for detection was equal regardless of the number of categories memorized. To explain the lack of automatization in visual detection in 70+ year old individuals, 3 experiments were carried out. The first presented an extremely simple visual search task in which it has been shown that young adults achieved automatization in relatively few training trials. Contrary to expectation automatic detection did not occur for the 70+ year old subjects. The second and third studies investigated different methods of training. One method used "massed" practice while the second method limited responses only to detection responses. Both novel practice methods failed to yield automatic detection in visual/memory search. Continued work in studying the development, or lack thereof, of automatization in later life will center on investigating its generality to nonsearch domains, to intermediate components leading to the automatized search process, and to other criteria in determining the degree of automatization. The significance of this project lies in mapping out and accounting for maturational changes in the development of automatic visual detection which play such an important part of our daily lives.